PT terracotta 12.5kg

Traditional terracotta (calcareous) earthenware clay. Its calcium carbonate content (19%) allows displaying an interesting palette of colours, from pink to straw colours, depending on the firing temperature and atmosphere. Its coefficient of thermal expansion is ideal for standard pottery glazes, in both single and twice firing processes. Its high resistance to frost and environmental degradation make it ideal for pieces exposed outdoors (garden pots, tiles, etc.). Available in powder (dry form) and extruded body (moist form) in a wide range of water content depending on the shaping application: wheel-throwing, modelling and shaping processes (extruding and pressing).

Firing range*: 990-1085ºC / Cone 07-04
Water content (throwing): 22%
Plasticity (IP Atterberg): 18
Carbonate content (CaCO3): 22%
Drying shrinkage: 7.8%
Firing shrinkage (1000ºC): 0.8%
Porosity (water absorption at 1000ºC): 14.3%
Dry bending strength: 9.9 N/mm2
Fired bending strength (1000ºC): 31.2 N/mm2
Thermal coefficient (25-500ºC): 80.3x10^-7ºC^-1

Note on the raw colour
The 2025 formula was developed in response to the depletion of the main clay deposit used in the classic formula, which gave the PT clay its characteristic greenish raw colour. The components of the new formula maintain both the colour and physical properties of the clay after firing; however, the raw colour has now changed to a brown tone.

(*) Firing range recommended for the clay to develop its best performance, both in terms of technical and safety characteristics, under conventional firing conditions. The colour samples may show temperatures outside the recommended range to provide a broader view, but these are pieces fired under controlled conditions. Cone equivalence according to Orton table for self-supporting cones, regular-SSB and 150ºC/hr heating rate.